Variable displacement type swash plate compressor

ABSTRACT

A variable displacement swash plate type compressor includes a crank chamber, a suction chamber, a drive shaft, a swash plate, and a bleeding passage connecting the crank chamber and the suction chamber. The bleeding passage has an axial passage and first and second radial passages in the drive shaft. The second radial passage opens on an outer peripheral surface of the drive shaft at a position that is closer to the swash plate than the first radial passage. The first radial passage is in constant communication with the crank chamber. The drive shaft has a valve member that is movable in the axial direction with the swash plate. The second radial passage is connected to the crank chamber when the swash plate is at maximum or minimum inclination angles and disconnected from the crank chamber by the valve member when the swash plate is at an intermediate inclination angle.

BACKGROUND OF THE INVENTION

The present invention relates to a variable displacement swash plate type compressor.

Japanese Unexamined Patent Application Publication No. 2006-132446 discloses a variable displacement swash plate type compressor (hereinafter simply referred to as compressor). The compressor includes a housing, a drive shaft, a swash plate, a piston, and a control mechanism. The housing includes a cylinder block having therethrough a cylinder bore, a first housing member cooperating with the cylinder block to define a crank chamber between the first housing member and the cylinder block, and a second housing member having therein a discharge chamber and a suction chamber. The drive shaft is rotatably supported in the housing, and has thereon a lug member which is disposed in the crank chamber.

The swash plate is rotatably supported on the drive shaft for rotation with the drive shaft and faces the lug member in the crank chamber. The piston is reciprocally movable in the cylinder bore with a stroke length depending on the inclination angle of the swash plate, thereby forming a compression chamber in the cylinder bore. The compressor further has a shaft hole, a sealing member, and a communication passage formed in the first housing member. The shaft hole for receiving the drive shaft is connected to the crank chamber. The sealing member is disposed outward of the crank chamber and the shaft hole in the compressor in the axial direction of the drive shaft. The sealing member supports the drive shaft to be rotatable and creates a tight seal between crank chamber and outside of the housing. The communication passage extends so as to intersect with the drive shaft. The communication passage opens to the crank chamber at one end thereof and opens at another end thereof between the shaft hole and the sealing member.

The control mechanism has a feeding passage connecting the discharge chamber and the crank chamber, a bleeding passage connecting the crank chamber and the suction chamber, and a displacement control valve. The control mechanism is configured to control the inclination angle of the swash plate with the pressure in the crank chamber. The displacement control valve is configured to adjust the opening degree of the feeding passage. The bleeding passage includes an axial passage, first radial passages, and second radial passages. The axial passage extends in the drive shaft in the axial direction of the drive shaft. The first and the second radial passages communicate with the axial passage in the drive shaft and extend from the axial passage in the radial direction of the drive shaft to open on an outer peripheral surface of the drive shaft. Specifically, the first radial passages are located outward of the crank chamber and open on the outer peripheral surface of the drive shaft between the lug member and the sealing member. The first radial passages are in constant communication with the crank chamber through the communication passage. The second radial passages open on the outer peripheral surface of the drive shaft at positions near the swash plate, where a refrigerant gas contains smaller amount of lubricant compared to the refrigerant gas exists in other locations in the crank chamber. The compressor further includes a valve member that is axially movable on the drive shaft along with the swash plate.

In this compressor, the inclination angle of the swash plate decreases as the pressure within the crank chamber is increased by the control mechanism, with the result that the discharge volume per rotation of the drive shaft decreases.

While on the other hand, the inclination angle of the swash plate increases as the pressure within the crank chamber is decreased by the control mechanism, with the result that the discharge volume per rotation of the drive shaft increases. When the inclination angle of the swash plate is the maximum or the minimum inclination angles, the valve member axially moves on the drive shaft to close the openings of the second radial passages on the drive shaft, therefore, the second radial passages are disconnected from the crank chamber by the valve member, which prevents the refrigerant gas in the crank chamber from being introduced from the second radial passages into the suction chamber through the axial passage. While the inclination angle of the swash plate is an intermediate inclination angle, which is smaller than the maximum inclination angle and greater than the minimum inclination angle, the valve member allows the second radial passages to connect to the crank chamber. As a result, the refrigerant gas in the crank chamber is introduced from each of the first and the second radial passages into the suction chamber through the axial passage. Since the refrigerant gas existing near the swash plate contains small amount of lubricant as described above, the refrigerant gas introduced from the crank chamber into the suction chamber through the second radial passages and the axial passage contains smaller amount of lubricant than the refrigerant gas introduced from the crank chamber into the suction chamber through the first radial passages and the axial passage. In this compressor, the second radial passages are connected to the crank chamber. This configuration enables the reduction of the flow rate of the refrigerant gas introduced from the crank chamber into the suction chamber through the first radial passages and the axial passage, while lubricant does not flow excessively from the crank chamber into the suction chamber.

In the adjustment of the pressure within the crank chamber, this configuration of the compressor enables to secure the flow rate of the refrigerant gas introduced from the crank chamber into the suction chamber through the first and the second radial passages and the axial passage, while controlling the amount of the lubricant introduced with the refrigerant gas from the crank chamber to the suction chamber. Accordingly, this compressor is capable of securing the lubricant in the crank chamber to lubricate inside the crank chamber while exhibiting high pressure controllability, which leads to high durability of the compressor.

However, a compressor having higher durability while having higher controllability is requested. In this compressor, the crank chamber and the second radial passages do not communicate with each other when the inclination angle of the swash plate is the minimum inclination angle, so that flow rate of the refrigerant gas with the lubricant introduced from the crank chamber into the suction chamber through the first radial passages and the axial passage increases. There is a case in that the refrigerant gas with the lubricant introduced from the crank chamber into the suction chamber is introduced into the compression chamber, and then discharged through the discharge chamber to a condenser outside the compressor, even at the minimum inclination angle of the swash plate and minimum discharge volume. Also, at the minimum inclination angle of the swash plate, the lubricant introduced with the refrigerant gas into the crank chamber decreases because the flow rate of the refrigerant gas introduced from an evaporator outside the compressor into the suction chamber decreases. Therefore, this compressor may cause the shortage of the lubricant in the crank chamber and is difficult to further improve its durability.

The present invention, which has been made in light of the above described problems, is directed to providing a variable displacement swash plate type compressor that has higher durability and controllability.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there is provided a variable displacement swash plate type compressor including a housing, a drive shaft, a swash plate, a piston, and a control mechanism. The housing has a discharge chamber, a suction chamber, a crank chamber, and a cylinder bore. The drive shaft is rotatably supported in the crank chamber. The swash plate is disposed in the crank chamber and supported on the drive shaft for rotation with the drive shaft. The piston is reciprocally movable in the cylinder bore with a stroke length depending on an inclination angle of the swash plate. The piston forms a compression chamber in the cylinder bore. The control mechanism is configured to change the inclination angle of the swash plate between a maximum inclination angle and a minimum inclination angle by a pressure within the crank chamber. The control mechanism has a feeding passage connecting the discharge chamber and the crank chamber, a bleeding passage connecting the crank chamber and the suction chamber, and a displacement control valve. The displacement control valve is configured to adjust at least one of an opening degree of the feeding passage and the bleeding passage. The bleeding passage has an axial passage, a first radial passages, and at least one second radial passage. The axial passage is formed in the drive shaft in an axial direction of the drive shaft. The first radial passage is formed in the drive shaft, communicates with the axial passage and extends in a radial direction of the drive shaft to open on an outer peripheral surface of the drive shaft in the crank chamber. The second radial passage is formed in the drive shaft, communicates with the axial passage and extends in the radial direction of the drive shaft to open on the outer peripheral surface of the drive shaft at a position that is closer to the swash plate than the first radial passage is to the swash plate. A valve member is disposed on the drive shaft. The valve member is movable in the axial direction of the drive shaft with the swash plate. The first radial passage is in constant communication with the crank chamber. The valve member is configured to connect the second radial passage to the crank chamber when the swash plate is at the maximum inclination angle or the minimum inclination angle and to disconnect the second radial passage from the crank chamber when the swash plate is at an intermediate inclination angle that is smaller than the maximum inclination angle and greater than the minimum inclination angle.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention together with objects and advantages thereof, may best be understood by reference to the following description of the embodiments together with the accompanying drawings in which:

FIG. 1 is a longitudinal cross-sectional view of a compressor according to a first embodiment of the present invention, showing a state of a swash plate in its maximum inclination;

FIG. 2 is a longitudinal cross-sectional view of the compressor of FIG. 1, showing a state of the swash plate in its intermediate inclination;

FIG. 3 is a longitudinal cross-sectional view of the compressor of FIG. 1, showing a state of the swash plate in its minimum inclination;

FIG. 4 is a fragmentary cross-sectional view of first radial passages and an axial passage taken along line IV-IV in FIG. 1;

FIG. 5 is a fragmentary cross-sectional view of second radial passages and the axial passage taken along line V-V in FIG. 1;

FIG. 6 is a graph showing a relationship between the inclination angle of the swash plate and the sum of the opening areas of the first and the second radial passages, according to the first embodiment of the present invention; and

FIG. 7 is a schematic enlarged plan view showing second radial passages in a compressor according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following will describe a variable displacement single-head swash plate type compressor (hereinafter simply referred to as the compressor) according to two embodiments of the present invention with reference to the accompanying drawings. The compressor according to the embodiments is mounted on a vehicle and forms a part of a refrigeration circuit of an air conditioner of the vehicle.

First Embodiment

Referring to FIGS. 1 to 3, there is shown a compressor according to a first embodiment. The compressor includes a housing 1, a drive shaft 3, a swash plate 5, a plurality of pistons 7, and a control mechanism 9.

In FIG. 1, the left side and the right side of the figure will be referred to as the front and the rear of the compressor. The upper side and the lower side of FIG. 1 will be referred to as the upper and the lower of the compressor. Directions indicated in FIGS. 2 to 7 excluding FIG. 6 correspond to the directions indicated in FIG. 1. The directions described in two embodiments are merely exemplary and the compressor of the present invention may be mounted appropriately in various postures depending on the vehicle on which the compressor is mounted.

The housing 1 includes a first housing member 13, a second housing member 15, a cylinder block 17, and a valve forming plate unit 19. The first housing member 13 forms a front part of the compressor. The second housing member 15 forms a rear part of the compressor. The cylinder block 17 is disposed between the first housing member 13 and the second housing member 15.

The first housing member 13 includes a front wall 13 a and a peripheral wall 13 b. The front wall 13 a extends in the vertical direction of the compressor on a front side of the compressor. The peripheral wall 13 b is integrally formed with and extends backward from the front wall 13 a, so that the first housing member 13 is formed in an approximately cylindrical-bottomed shape by the front wall 13 a and the peripheral wall 13 b. The front wall 13 a and the peripheral wall 13 b of the first housing member 13 and the cylinder block 17 cooperate to define a crank chamber 21 in the first housing member 13.

The first housing member 13 further has a boss 13 c, a first shaft hole 13 d, and a communication passage 13 e. The boss 13 c projects forward from the front wall 13 a, and has therein a first accommodation space 130. The first accommodation space 130 spatially extends backward from the front end of the boss 11 c. The boss 13 c accommodates a sealing member 23 in the first accommodation space 130. The first shaft hole 13 d extends in the longitudinal direction of the compressor and connects the first accommodation space 130 and the crank chamber 21. The first housing member 13 has a first slide bearing 25 a in the first shaft hole 13 d.

The communication passage 13 e extends obliquely in the longitudinal direction of the compressor and connects the first accommodation space 130 and the crank chamber 21. Specifically, the front end of the communication passage 13 e opens to the first accommodation space 130 at a position behind the sealing member 23. The rear end of the communication passage 13 e opens to the crank chamber 21 at a position in front of a lug member 41. Accordingly, the first accommodation space 130 communicates with the crank chamber 21 through the communication passage 13 e. Details of the lug member 41 will be described later.

The second housing member 15 has a suction chamber 15 a, a discharge chamber 15 b, an annular wall 15 c, an outer peripheral wall 15 d, a suction port 15 e, a second accommodation space 15 f, and a discharge port 15 g. The suction chamber 15 a is defined by the annular wall 15 c and located in the radial center of the second housing member 15. The discharge chamber 15 b is defined by the annular wall 15 c and the outer peripheral wall 15 d and is located radially outward of the suction chamber 15 a, so that the discharge chamber 15 b has an annular shape and surrounds the suction chamber 15 a.

The suction port 15 e extends in the second housing member 15 in the longitudinal direction of the compressor and opens to suction chamber 15 a at the front end of the suction port 15 e. The suction port 15 e opens on the rear surface of the second housing member 15 at the rear end of the suction port 15 e. Accordingly, the suction port 15 e connects the suction chamber 15 a and the outside of the compressor. The second accommodation space 15 f communicates with the discharge chamber 15 b and extends in the second housing member 15 in the longitudinal direction of the compressor. The discharge port 15 g extends vertically in the second housing member 15 and the upper end of the discharge port 15 g opens on the upper surface of the second housing member 15. The discharge port 15 g communicates with the discharge chamber 15 b through the second accommodation space 15 f.

The second housing member 15 includes a discharge check valve mechanism 27 disposed in the second accommodation space 15 f. The discharge check valve mechanism 27 includes a valve case 27 a, a check valve body 27 b, and a first coil spring 27 c. The discharge check valve mechanism 27 is configured to connect or disconnect the discharge chamber 15 b to the outside of the compressor.

The valve case 27 a is fixed inside the second accommodation space 15 f of the second housing member 15 by a circlip 29. The valve case 27 a has a first communication hole 271 and a second communication hole 272. The first communication hole 271 connects inside of the valve case 27 a and the discharge chamber 15 b of the second housing member 15. The second communication hole 272 connects inside of the valve case 27 a and the discharge port 15 g. The check valve body 27 b is movably accommodated in the valve case 27 a. The first coil spring 27 c is disposed in the valve case 27 a and urges the check valve body 27 b forward.

The second housing member 15 has a first feeding passage 31 a, a second feeding passage 31 b, and a displacement control valve 33. The first feeding passage 31 a connects the discharge chamber 15 b and the displacement control valve 33. The second feeding passage 31 b is connected to the displacement control valve 33 at the rear end of the second feeding passage 31 b and opens on the front surface of the second housing member 15 at the front end of the second feeding passage 31 b. The displacement control valve 33 is configured to adjust the opening degree of the first and the second feeding passages 31 a, 31 b for adjusting the pressure within the crank chamber 21 in response to the external control of supplying electric power. Details of the displacement control valve 33 will be described later.

The cylinder block 17 has therein a plurality of cylinder bores 17 a. The cylinder bores 17 a are arranged circumferentially and equiangularly. Each of the cylinder bores 17 a communicates with the crank chamber 21 at the front end thereof. The cylinder block 17 further has a retainer groove 17 b that determines the maximum opening degree of a suction reed valve 191 a. Details of the suction reed valve 191 a will be described later.

The cylinder block 17 further has therein a spring chamber 17 c, a communication space 17 d, a second shaft hole 17 e, and a third feeding passage 31c. The spring chamber 17 c extends backward from the front surface of the cylinder block 17 and communicates with the crank chamber 21, so that the spring chamber 17 c forms a part of the crank chamber 21. The cylinder block 17 includes a return spring 35 disposed in the spring chamber 17 c. The return spring 35 urges the swash plate 5 toward the front side of the crank chamber 21 when the inclination angle of the swash plate 5 is at the minimum.

The communication space 17 d of the cylinder block 17 extends forward from the rear surface of the cylinder block 17. The cylinder block 17 further has a first thrust bearing 37 a and a second coil spring 39 disposed in the communication space 17 d. The second coil spring 39 is interposed between the first thrust bearing 37 a and the valve forming plate unit 19 to support and urge the first thrust bearing 37 a forward. The second shaft hole 17 e longitudinally extends to connect the spring chamber 17 c and the communication space 17d. The cylinder block 17 further has a second slide bearing 25 b disposed in the second shaft hole 17 e. The first and the second slide bearings 25 a, 25 b may be replaced by rolling bearings.

The third feeding passage 31 c longitudinally extends in the cylinder block 17. The third feeding passage 31 c opens to the crank chamber 21 at the front end of the third feeding passage 31 c and opens on the rear surface of the cylinder block 17 at the rear end of the third feeding passage 31c.

The valve forming plate unit 19 is disposed between the cylinder block 17 and the second housing member 15, and includes a valve plate 190, a suction valve plate 191, a discharge valve plate 192, and a retainer plate 193.

The valve forming plate unit 19 has the same number of suction holes 190 a and discharge holes 190 b as the cylinder bores 17 a. The suction holes 190 a are formed through the valve plate 190, the discharge valve plate 192, and the retainer plate 193. The discharge holes 190 b are formed through the valve plate 190 and the suction valve plate 191. The valve forming plate unit 19 further has a throttle passage 190 c and a third communication hole 190 d. The throttle passage 190 c and the third communication hole 190 d are formed through the valve plate 190, the suction valve plate 191, the discharge valve plate 192, and the retainer plate 193.

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Each cylinder bore 17 a communicates with the suction chamber 15 a through the suction hole 190 a, and also communicates with the discharge chamber 15 b through the discharge hole 190 b. The throttle passage 190 c connects the communication space 17 d and the suction chamber 15 a. The third communication hole 190 d connects the second feeding passage 31 b and the third feeding passage 31 c.

The suction valve plate 191 is disposed on the front surface of the valve plate 190, and includes the suction reed valves 191 a, which are elastically deformable so as to open or close the suction holes 190 a. The discharge valve plate 192 is disposed on the rear surface of the valve plate 190, and has discharge reed valves 192 a, which are elastically deformable so as to open or close the discharge holes 190 b. The retainer plate 193 is disposed on the rear surface of the discharge valve plate 192 to determine the maximum opening degree of each discharge reed valve 192 a.

In this compressor, the first to the third feeding passages 31 a to 31 c and the third communication hole 190 d cooperate to form a feeding passage 31. The second and the third feeding passages 31 b, 31 c and the third communication hole 190 d cooperate to connect the crank chamber 21 and the displacement control valve 33. Accordingly, the feeding passage 31 and the displacement control valve 33 cooperate to connect the crank chamber 21 and the discharge chamber 15 b.

The drive shaft 3 has an outer peripheral surface 30 and extends longitudinally through the first housing member 13 and the cylinder block 17. Specifically, the drive shaft 3 is inserted in the boss 13 c and extends backward longitudinally through the crank chamber 21 to be inserted in the cylinder block 17. More specifically, the drive shaft 3 is inserted into the sealing member 23 in the first accommodation space 130 at the front end of the drive shaft 3. The drive shaft 3 is supported by the first slide bearing 25 a in the first shaft hole 13d and by the second slide bearing 25 b in the second shaft hole 17 e. The drive shaft 3 is also supported by the first thrust bearing 37 a in the communication space 17 d at the rear end of the drive shaft 3. Accordingly, the drive shaft 3 is supported in the crank chamber 21 so as to rotate about the axis O of the drive shaft 3 that is parallel to the longitudinal direction of the compressor. The sealing member 23 holds the drive shaft 3 to be rotatable and seals off the crank chamber 21 from outside of the first housing member 13.

The drive shaft 3 has a threaded portion 3 a at the front end thereof and is connected to a pulley or an electromagnetic clutch (not shown) at the threaded portion 3 a.

The drive shaft 3 has thereon the lug member 41, the swash plate 5, a valve member 43, and a third coil spring 45. The lug member 41 is press-fit to the drive shaft 3, so that the lug member 41 is rotatable with the drive shaft 3 in the crank chamber 21. The lug member 41 has a second thrust bearing 37 b disposed between the front wall 13 a of the first housing member 13 and the lug c member 41.

The lug member 41 includes a pair of lug arms 41 a. The lug arms 41 a are disposed adjacent to each other and extends backward from the lug member 41. The lug member 41 further includes a pair of guide faces 41 b disposed between the lug arms 41 a. The guide faces 41 b extend obliquely backward from the outer periphery side of the lug member 41 toward the axis O of the drive shaft 3. The drawings such as FIG. 1 show one lug arm 41 a and one guide face 41 b.

The swash plate 5 is disposed behind the lug member 41 in the crank chamber 21 such that the lug member 41 faces the swash plate 5. The swash plate 5 is formed in an approximate disc shape and has a front surface 5 a and a rear surface 5 b that face frontward and rearward, respectively. The swash plate 5 further has an insertion hole 5 c, an abutment portion 5 d, and a weight portion 5 e.

The insertion hole 5 c passes through the swash plate 5 from the front surface 5 a to the rear surface 5 b for receiving the drive shaft 3, so that the swash plate 5 is supported on the drive shaft 3 for rotation with the drive shaft 3. The abutment portion 5 d projects toward the drive shaft 3 in the insertion hole 5c to abut on the outer peripheral surface 30 of the drive shaft 3 in the insertion hole 5 c. The weight portion 5 e of the swash plate 5 is formed in an approximate semi-cylindrical shape and extends forward from the front surface 5 a of the swash plate 5. The weight portion 5 e includes a pressing surface 500. The pressing surface 500 extends obliquely toward the axis O of the drive shaft 3 and is formed continuously from the abutment portion 5 d in the insertion hole 5 c of the swash plate 5.

The swash plate 5 further includes a pair of swash plate arms 5f. The swash plate arms 5 f are disposed adjacent to each other and extend forward from the front surface 5 a of the swash plate 5. The swash plate arms 5 f are located opposite to the abutment portion 5 d and the weight portion 5 e across the axis O of the drive shaft 3. The drawings such as FIG. 1 show one of the swash plate arms 5f.

In this compressor, the swash plate 5 is mounted on the drive shaft 3 such that the swash plate arms 5 f are located between the lug arms 41 a. The lug member 41 and the swash plate 5 are coupled to each other such that the swash plate arms 5 f are located between the lug arms 41 a. This configuration enables the swash plate 5 to rotate with the lug member 41 in the crank chamber 21 by the rotary movement of the drive shaft 3 transmitted through the lug arms 41 a to the swash plate arms 5 f.

The swash plate arms 5 f are located between the lug arms 41 a, so that the swash plate arms 5 f abut and slide on the guide faces 41 b at the front ends of the swash plate arms 5 f. This configuration enables the swash plate 5 to change its inclination angle to the maximum inclination angle shown in FIG. 1, the intermediate inclination angle in FIG. 2, or the minimum inclination angle in FIG. 3 with respect to an imaginary plane perpendicular to the axis O of the drive shaft 3. The intermediate inclination angle of the swash plate 5 is an angle that is smaller than the maximum inclination angle and is greater than the minimum inclination angle. In this compressor, the intermediate inclination angle of the swash plate 5 has a certain definite range between the maximum inclination angle and the minimum inclination angle, more specifically, the intermediate inclination angle is an angle of the swash plate 5 while the valve member 43 is covering whole the openings of the second radial passages 55 a to 55 c on the outer peripheral surface 30 of the drive shaft 3. Details of the valve member 43 will be described later.

The valve member 43 is formed in a ring shape and has a front end face 43 a, a rear end face 43 b, and a tapered surface 43 c formed continuously from the front end face 43 a to the rear end face 43 b to decrease the diameter. The valve member 43 is tapered from the front end face 43 a to the rear end face 43 b. The valve member 43 is disposed between the lug member 41 and the swash plate 5. The third coil spring 45 is disposed between the lug member 41 and the front end face 43 a of the valve member 43. The drive shaft 3 is inserted into the valve member 43 and the third coil spring 45. The third coil spring 45 urges the valve member 43 backward in the crank chamber 21. In this compressor, as shown in FIGS. 1 to 3, the tapered surface 43 c of the valve member 43 constantly abuts on the pressing surface 500 of the swash plate 5 regardless of the inclination angle of the swash plate 5. This configuration enables the valve member 43 to axially slide on the outer peripheral surface 30 of the drive shaft 3 between the lug member 41 and the swash plate 5 in conjunction with the inclination of the swash plate 5.

The pistons 7 are reciprocally movable in the respective cylinder bores 17 a, respectively. Each piston 7 and the valve forming plate unit 19 cooperate to define a compression chamber 47 in the cylinder bore 17 a.

The pistons 7 each have a recess 7 a for engagement. The recess 7 a has therein semi-spherical shoes 49 a, 49 b. The shoes 49 a, 49 b serve as a conversion mechanism that is configured to convert the rotary movement of the swash plate 5 to the reciprocating movement of the piston 7. This configuration enables the piston 7 to be reciprocally movable in the cylinder bore 17 a with a stroke length depending on the inclination angle of the swash plate 5. The shoes 49 a, 49 b may be replaced by a wobble type conversion mechanism including a thrust bearing for supporting a wobble plate on the rear surface 5 b of the swash plate 5 and connecting rods for connecting the wobble plate and the pistons 7.

The drive shaft 3 has therein an axial passage 51, first radial passages 53 a to 53 c (FIG. 4), the second radial passages 55 a to 55 c (FIG. 5), and a third radial passage 57 (FIGS. 1 to 3).

The axial passage 51 extends in the drive shaft 3 in the axial direction of the drive shaft 3 and communicates with the communication space 17 d at the rear end of the axial passage 51. The axial passage 51 has a larger diameter than that of the throttle passage 190 c.

The first radial passages 53 a to 53 c are located in the rear part of the drive shaft 3. As shown in FIG. 4, each of the first radial passages 53 a to 53 c communicates with the axial passage 51and extends from the axial passage 51 in the radial direction of the drive shaft 3 to open on the outer peripheral surface 30 of the drive shaft 3 at intervals in the circumferential direction of the drive shaft 3. Specifically, the first radial passages 53 b, 53 c extend in opposite directions, which are perpendicular to the first radial passage 53 a, with respect to the axis O of the drive shaft 3 and open on the outer peripheral surface 30 of the drive shaft 3. Each of the first radial passages 53 a to 53 c has a larger diameter than that of the throttle passage 190 c shown in FIGS. 1 to 3.

The second radial passages 55 a to 55 c are formed at the approximate longitudinal center of the drive shaft 3, that is, disposed in front of the first radial passages 53 a to 53 c. As shown in FIG. 5, each of the second radial passages 55 a to 55 c communicates with the axial passage 51 and extends from the axial passage 51 in the radial direction of the drive shaft 3 to open on the outer peripheral surface 30 of the drive shaft 3 at intervals in the circumferential direction of the drive shaft 3 as well as the first radial passages 53 a to 53 c. Specifically, the second radial passages 55 b, 55 c extend in opposite directions, which are perpendicular to the second radial passage 55 a, with respect to the axis O of the drive shaft 3 and open on the outer peripheral surface 30 of the drive shaft 3. The second radial passages 55 a to 55 c each have the same diameter as the first radial passages 53 a to 53 c, that is, each of the second radial passages 55 a to 55 c has a larger diameter than that of the throttle passage 190 c shown in FIGS. 1 to 3.

As shown in FIG. 1, the third radial passage 57 is formed in the front part of the drive shaft 3 in front of the first and second radial passages 53 a to 53 c, 55 a to 55 c. The third radial passage 57 communicates with the axial passage 51 and extends from the axial passage 51 in the radial direction of the drive shaft 3 to open on the outer peripheral surface 30 of the drive shaft 3. The third radial passage 57 has the same diameter as each of the first and second radial passages 53 a to 53 c, 55 a to 55 c, that is, the third radial passage 57 has a larger diameter than that of the throttle passage 190 c.

In this compressor, the drive shaft 3 is inserted into the first housing member 13 and the cylinder block 17, so that the first radial passages 53 a to 53 c are positioned in the spring chamber 17 c, that is, positioned on the rear side of the crank chamber 21. The first radial passages 53 a to 53 c are in constant communication with the crank chamber 21.

When the swash plate 5 is at the maximum inclination angle, the second radial passages 55 a to 55 c are positioned in the insertion hole 5 c of the swash plate 5 at the approximate longitudinal center of the crank chamber 21, in other words, the second radial passages 55 a to 55 c open on the outer peripheral surface 30 of the drive shaft 3 in the crank chamber 21 at positions that are closer to the swash plate 5 than the first radial passages 53 a to 53 c are to the swash plate 5. The first radial passages 53 a to 53 c open on the outer peripheral surface 30 of the drive shaft 3 in the crank chamber 21 at positions that are closer to the cylinder bores 17 a than the second radial passages 55 a to 55 c are to the cylinder bores 17 a.

The drive shaft 3 and the swash plate 5 are positioned such that the second radial passages 55 a to 55 c and the abutment portion 5 d do not face each other in the insertion hole 5 c of the swash plate 5. That is, the second radial passages 55 a to 55 c open on the outer peripheral surface 30 of the drive shaft 3 at positions that are spaced from the abutment portion 5 d in the circumferential direction of the drive shaft 3. In this compressor, the second radial passages 55 a to 55 c are connected to or disconnected from the crank chamber 21 by the axial movement of the valve member 43 on the drive shaft 3. This connecting system between the second radial passages 55 a to 55 c and the crank chamber 21 will be described later.

The third radial passage 57 is positioned in the first accommodation space 130, specifically, positioned between the sealing member 23 and the lug member 41. The first accommodation space 130 communicates with the crank chamber 21 through the communication passage 13e, so that the third radial passage 57 in the first accommodation space 130 is in constant communication with the crank chamber 21.

In this compressor, the axial passage 51, the first radial passages 53 a to 53 c, the second radial passages 55 a to 55 c, the third radial passage 57, the communication space 17 d, and the throttle passage 190 c cooperate to form a bleeding passage 59, so that the crank chamber 21 communicates with the suction chamber 15 a through the bleeding passage 59. The feeding passage 31, the bleeding passage 59 and the displacement control valve 33 cooperate to form the control mechanism 9.

In this compressor, the suction port 15 e is connected to an evaporator through a pipe. The discharge port 15 g is connected to a condenser through a pipe. The evaporator and the condenser are connected through the pipes and an expansion valve. The evaporator, the expansion valve, the condenser, and the compressor cooperate to form a refrigeration circuit of a vehicle air conditioner. The evaporator, the expansion valve, the condenser, and the pipes are not shown in the drawings.

In this compressor, each piston 7 makes a reciprocating movement in the cylinder bore 17 a in response to the rotation of the swash plate 5 caused by the rotary movement of the drive shaft 3. The compression chamber 47 changes its volume depending on the stroke length of the piston 7. The refrigerant gas, which flows from the evaporator into the suction chamber 15 a through the suction port 15 e, is introduced from the suction chamber 15 a into the compression chamber 47 to be compressed. The compressed refrigerant gas is discharged from the compression chamber 47 to the discharge chamber 15 b, and then discharged to the condenser through the discharge port 15 g. When the pressure within the discharge chamber 15 b is below a predetermined pressure value, as shown in FIG. 3, the first coil spring 27 c urges the check valve body 27 b to close the first and the second communication holes 271, 272 so as to prevent the back-flow of the refrigerant gas from the condenser to the discharge chamber 15 b. However, the check valve body 27 b may not completely close the first and the second communication holes 271, 272 so as to discharge a small flow rate of refrigerant gas, which is discharged from the compression chamber 47 to the discharge chamber 15 b, to the condenser.

In this compressor, the control mechanism 9 is configured to adjust the pressure within the crank chamber 21 so as to adjust the discharge volume of the compressor.

Specifically, the displacement control valve 33 of the control mechanism 9 adjusts the opening degree of the feeding passage 31, which is formed by the first to the third feeding passages 31 a to 31 c and the third communication hole 190 d. The refrigerant gas at high pressure is introduced from the discharge chamber 15 b into the crank chamber 21 through the feeding passage 31. Then, the refrigerant gas in the crank chamber 21 is introduced into the suction chamber 15 a through the bleeding passage 59, which is formed by the axial passage 51, the first radial passages 53 a to 53 c, the second radial passages 55 a to 55 c, the third radial passage 57, the communication space 17 d and the throttle passage 190 c. The adjustment of the opening degree by the displacement control valve 33 of the control mechanism 9 controls the balance between the flow rate of the high pressure refrigerant gas introduced from the discharge chamber 15 b into the crank chamber 21 through the feeding passage 31 and the flow rate of the refrigerant gas introduced from the crank chamber 21 into the suction chamber 15 a through the bleeding passage 59. The balance between these two flow rates determines the pressure within the crank chamber 21. The change in the pressure within the crank chamber 21 varies the differential pressure between the crank chamber 21 and the compression chambers 47, thereby changing the inclination angle of the swash plate 5. The inclination angle of the swash plate 5 determines the stroke length of each piston 7 to adjust the discharge volume of the compressor.

Accordingly, in this compressor, the pressure within the crank chamber 21 increases as the displacement control valve 33 increases the opening degree of the feeding passage 31, so that the swash plate 5 decreases its inclination angle with the abutment portion 5 d abutting on the outer peripheral surface 30 of the drive shaft 3. The decreasing inclination angle of the swash plate 5 decreases the stroke length of each piston 7, thereby decreasing the discharge volume per rotation of the drive shaft 3. Conversely, the pressure within the crank chamber 21 decreases as the displacement control valve 33 decreases the opening degree of the feeding passage 31, so that the swash plate 5 increases its inclination angle with the abutment portion 5 d abutting on the outer peripheral surface 30 of the drive shaft 3. The increasing inclination angle of the swash plate 5 increases the stroke length of each piston 7, thereby increasing the discharge volume per rotation of the drive shaft 3.

In this compressor, the drive shaft 3 has therein the first radial passages 53 a to 53 c, the second radial passages 55 a to 55 c, and the third radial passage 57 that communicate with the axial passage 51, and the refrigerant gas in the crank chamber 21 is introduced into the suction chamber 15 a through the first radial passages 53 a to 53 c and the second radial passages 55 a to 55 c. This configuration enables the flow rate control of the refrigerant gas introduced from the third radial passage 57 to the axial passage 51. The throttle passage 190 c has a smaller diameter than those of the axial passage 51, the first radial passages 53 a to 53 c, the second radial passages 55 a to 55 c and the third radial passage 57, so that the throttle passage 190 c enables to lead the refrigerant gas to the suction chamber 15 a at a preferred pressure.

In this compressor, each cylinder bore 17 a positioned adjacent to the rear part of the crank chamber 21 leaks blow-by gas containing a relatively large amount of lubricant, so that the refrigerant gas presents in the rear part of the crank chamber 21 contains a relatively large amount of lubricant. The lubricant is sprinkled by the rotation of the drive shaft 3 and the swash plate 5 radially and outwardly in the crank chamber 21, and flows down in the crank chamber 21 from the peripheral wall 13 b to the front wall 13 a, so that the plenty of lubricant presents in the front part of the crank chamber 21. That is, the refrigerant gas in the front part of the crank chamber 21 contains larger amount of lubricant than the refrigerant gas in the rear part of the crank chamber 21. On the other hand, the lubricant in the refrigerant gas existing around the longitudinal center of the crank chamber 21, specifically, the lubricant in the refrigerant gas existing around the insertion hole 5 c of the swash plate 5 is reduced because the lubricant is sprinkled by the rotation of the drive shaft 3 and the swash plate 5 radially and outwardly in the crank chamber 21.

Accordingly, the refrigerant gas flowing from the communication passage 13 e through the third radial passage 57 to the axial passage 51 contains larger amount of lubricant than the refrigerant gas introduced from the first radial passages 53 a to 53 c or the second radial passages 55 a to 55 c to the axial passage 51. The refrigerant gas introduced from the first radial passages 53 a to 53 c to the axial passage 51 contains larger amount of lubricant than the refrigerant gas introduced from the second radial passages 55 a to 55 c to the axial passage 51. In other words, the refrigerant gas introduced from the second radial passages 55 a to 55 c to the axial passage 51 contains the smallest amount of lubricant.

In this compressor, the refrigerant gas containing the lubricant in the crank chamber 21 is introduced into the suction chamber 15 a through the third radial passage 57, the axial passage 51, the communication space 17 d, and the throttle passage 190 c to adjust the pressure within the crank chamber 21, so that the lubricant in the refrigerant gas suitably lubricates the second thrust bearing 37 b, the sealing member 23 and the first slide bearing 25 a. Particularly, the sealing member 23 is lubricated constantly because the third radial passage 57 is in constant communication with the crank chamber 21 through the first accommodation space 130 and the communication passage 13 e.

In this compressor, the valve member 43 moves on the drive shaft 3 in the axial direction of the drive shaft 3 in conjunction with the inclination of the swash plate 5, so that the sum of the opening areas of the first radial passages 53 a to 53 c and the second radial passages 55 a to 55 c changes depending on the inclination angle of the swash plate 5 as shown in FIG. 6. Specifically, the sum of the opening areas of the first radial passages 53 a to 53 c and the second radial passages 55 a to 55 c reaches the maximum level at the minimum inclination angle or the maximum inclination angle of the swash plate 5. The sum of the opening areas gradually decreases with the increasing inclination angle of the swash plate 5 from the minimum inclination angle to the intermediate inclination angle. The sum of the opening areas is kept to the minimum level while the swash plate 5 is at the intermediate inclination angle. Then, the sum of the opening areas gradually increases with the increasing inclination angle of the swash plate 5 from the intermediate inclination angle to the maximum inclination angle. In this compressor, since the first radial passages 53 a to 53 c are in constant communication with the crank chamber 21, the opening areas of the first radial passages 53 a to 53 c are maintained constant, which does not reduce the sum of the opening areas of the first radial passages 53 a to 53 c and the second radial passages 55 a to 55 c to zero. The operation according to the change in the sum of the opening areas of the first radial passages 53 a to 53 c and the second radial passages 55 a to 55 c is described below.

In this compressor, as shown in FIG. 1, when the inclination angle of the swash plate 5 is at the maximum, the pressing surface 500 presses the valve member 43 on the drive shaft 3 axially toward the front part of the crank chamber 21 to move the valve member 43 away from the openings of the second radial passages 55 a to 55 c on the outer peripheral surface 30 of the drive shaft 3. That is, when the inclination angle of the swash plate 5 is at the maximum, the second radial passages 55 a to 55 c are connected to the crank chamber 21 and reach their maximum opening areas as described above. Accordingly, the refrigerant gas in the crank chamber 21 is introduced from each of the first radial passages 53 a to 53 c, the second radial passages 55 a to 55 c, and the third radial passage 57 into the suction chamber 15 a through the axial passage 51, the communication space 17 d, and the throttle passage 190 c. When the sum of the opening areas of the first radial passages 53 a to 53 c and the second radial passages 55 a to 55 c is maximum, this compressor enables the reduction of the flow rate of the refrigerant gas introduced through the third radial passage 57 into the suction chamber 15 a while ensuring the overall flow rate of the refrigerant gas introduced from the crank chamber 21 into the suction chamber 15 a. Also, this compressor enables the decrease of the flow rate of the refrigerant gas introduced through the first radial passages 53 a to 53 since the refrigerant gas is introduced through the second radial passages 55 a to 55 c in addition to the first radial passages 53 a to 53 c.

Since the refrigerant gas introduced through the second radial passages 55 a to 55 c from the crank chamber 21 contains only a small amount of lubricant as described above, the lubricant is not excessively introduced with the refrigerant gas through the second radial passages 55 a to 55 c into the suction chamber 15 a when the second radial passages 55 a to 55 c are connected to the crank chamber 21, and the certain amount of the lubricant is secured in the crank chamber 21. Accordingly, when the inclination angle of the swash plate 5 is at the maximum, this compressor enables the reduction of the lubricant introduced from the crank chamber 21 into the suction chamber 15 a while lubricating the sealing member 23 by the lubricant in the refrigerant gas introduced through the third radial passage 57. This compressor is unlikely to cause the insufficient lubrication in the crank chamber 21 when the inclination angle of the swash plate 5 is at the maximum.

In this compressor, the valve member 43 axially moves on the drive shaft 3 toward the rear part of the crank chamber 21 in conjunction with the decreasing inclination angle of the swash plate 5 from the maximum to gradually cover the openings of the second radial passages 55 a to 55 c on the outer peripheral surface 30 of the drive shaft 3, so that the sum of the opening areas of the first radial passages 53 a to 53 c and the second radial passages 55 a to 55 c gradually decreases as shown in FIG. 6 as the opening areas of the second radial passages 55 a to 55 c gradually decrease. Accordingly, the flow rate of the refrigerant gas introduced from the third radial passage 57 to the axial passage 51 gradually increases. As shown in FIG. 2, while the swash plate 5 is at the intermediate inclination angle, the valve member 43 covers the whole openings of the second radial passages 55 a to 55 c, and the second radial passages 55 a to 55 c are disconnected from the crank chamber 21 by the valve member 43 on the drive shaft 3. While the swash plate 5 is at the intermediate inclination angle, the refrigerant gas is not introduced from the crank chamber 21 into the suction chamber 15 a through the second radial passages 55 a to 55 c and the axial passage 51.

In this compressor, when the sum of the opening areas of the first radial passages 53 a to 53 c and the second radial passages 55 a to 55 c is minimum, the flow rate of the refrigerant gas introduced from the third radial passage 57 to the axial passage 51 increases, thus, the lubricant in the refrigerant gas introduced from the third radial passage 57 lubricates the sealing member 23 in the first accommodation space 130 suitably. As the opening areas of the second radial passages 55 a to 55 c gradually decrease, the flow rate of the refrigerant gas introduced from the first radial passages 53 a to 53 c to the axial passage 51 gradually increases. As a result, when the swash plate 5 is at the intermediate inclination angle, this compressor prevents or inhibits the excessive accumulation of the lubricant in the crank chamber 21 and the heat generation of the lubricant caused by the agitation by the swash plate 5 in the crank chamber 21. The prevention of the excessive lubricant accumulation in the crank chamber 21 enables this compressor to eliminate or minimize the insufficient circulation of the lubricant in the refrigeration circuit in which this compressor is included.

In this compressor, the valve member 43 further moves axially on the drive shaft 3 toward the rear part of the crank chamber 21 and gradually away from the openings of the second radial passages 55 a to 55 c on the outer peripheral surface 30 of the drive shaft 3 with the decreasing inclination angle of the swash plate 5 from the intermediate inclination angle, so that the opening areas of the second radial passages 55 a to 55 c gradually increase as the second radial passages 55 a to 55 c gradually open to the crank chamber 21. As shown in FIG. 3, when the inclination angle of the swash plate 5 is at the minimum, the valve member 43 is completely away from the openings of the second radial passages 55 a to 55 c and the second radial passages 55 a to 55c reach their maximum opening areas, thus, the sum of the opening areas of the first radial passages 53 a to 53 c and the second radial passages 55 a to 55c reaches the maximum level. That is, as well as the case for the maximum inclination angle, when the inclination angle of the swash plate 5 is at the minimum, this compressor enables the decrease of the flow rate of the refrigerant gas introduced through the third radial passage 57 into the suction chamber 15 a while ensuring decreasing the overall flow rate of the refrigerant gas introduced from the crank chamber 21 into the suction chamber 15 a. Accordingly, this compressor enables the reduction of the lubricant introduced from the crank chamber 21 to the suction chamber 15 a while ensuring the overall flow rate of the refrigerant gas introduced from the crank chamber 21 into the suction chamber 15 a.

When the discharge volume per rotation of the drive shaft 3 is reduced at the minimum inclination angle of the swash plate 5, this compressor may slightly flow the refrigerant gas, which was discharged from the compression chamber 47 to the discharge chamber 15 b, to the condenser. In this case, the lubricant, which was introduced with the refrigerant gas from the crank chamber 21 to the suction chamber 15 a, is to the compression chamber 47 and then discharger) to the condenser through the discharge chamber 15 b. When the inclination angle of the swash plate 5 is at the minimum, the lubricant flowing into the compressor with the refrigerant gas decreases because the flow rate of the refrigerant gas flowing from the evaporator into the suction chamber 15 a through the suction port 15 e decreases. However, even in this case, this compressor is unlikely to cause the insufficient lubrication in the crank chamber 21.

In the adjustment of the pressure within the crank chamber 21, this compressor enables the suitable control of the amount of the lubricant introduced with the refrigerant gas from the crank chamber 21 to the suction chamber 15 a while ensuring the flow rate of the refrigerant gas introduced from the crank chamber 21 to the suction chamber 15 a through the bleeding passage 59. Therefore, this compressor is capable of securing the lubricant in the crank chamber 21 depending on the inclination angle of the swash plate 5.

Accordingly, the compressor according to the first embodiment exhibits higher durability and controllability.

Particularly, this compressor has the first radial passages 53 a to 53 c in the drive shaft 3. This configuration enables the suitable control of the flow rate of the refrigerant gas introduced from the crank chamber 21 into the suction chamber 15 a through the first radial passages 53 a to 53 c and the axial passage 51. This compressor further has the second radial passages 55 a to 55 c in the drive shaft 3. This configuration enables the suitable control of the flow rate of the refrigerant gas introduced from the crank chamber 21 to the suction chamber 15 a through the second radial passages 55 a to 55 c and the axial passage 51 when the second radial passages 55 a to 55 c are connected to the crank chamber 21.

In this compressor, the openings of the second radial passages 55 a to 55 c are located away from the abutment portion 5 d in the circumferential direction of the drive shaft 3, so that the openings of the second radial passages 55 a to 55 c do not face the abutment portion 5 d, or, do not contact the abutment portion 5 d in the insertion hole 5 c of the swash plate 5. This configuration enables the suitable change of the inclination angle of the swash plate 5.

Second Embodiment

As shown in FIG. 7, the compressor according a second embodiment has three second radial passages, namely, second radial passages 61 a to 61 c in the drive shaft 3. As well as the second radial passages 55 a to 55 c according to the first embodiment, each of the second radial passages 61 a to 61 c communicates with the axial passage 51 and extends from the axial passage 51 in the radial direction of the drive shaft 3 to open on the outer peripheral surface 30 of the drive shaft 3 at the approximate longitudinal center of the drive shaft 3. The second radial passage 61 a has a larger diameter than those of the second radial passages 61 b, 61 c and is disposed behind the second radial passages 61 b, 61 c in the axial direction of the drive shaft 3. In this compressor, the second radial passages 61 a to 61 c are formed at positions where whole the second radial passages 61 a to 61 c are covered by the valve member 43 while the swash plate 5 is at the intermediate inclination angle. The structure of the compressor according to the second embodiment is otherwise similar to the compressor according to the first embodiment and will not be further elaborated here.

According to the second embodiment, the second radial passage 61 a has a larger diameter than those of the second radial passages 61 b, 61 c. This configuration enables the suitable adjustment of the opening degree of the second radial passages 61 a to 61 c along with the axial movement of the valve member 43. The operation of the compressor according to the second embodiment is otherwise similar to the compressor according to the first embodiment and will not be further elaborated here.

Although the present invention is described with the first and the second embodiments, the present invention is not limited thereto, and the invention may appropriately be modified within the gist of the present invention.

For example, instead of the third radial passage 57, the first radial passages 53 a to 53 c may be formed in the front part of the drive shaft 3 to open between the sealing member 23 and the lug member 41 on the outer peripheral surface 30 of the drive shaft 3.

The first radial passage of the present invention may be formed by the first radial passages 53 a only without the first radial passages 53 b, 53 c. The drive shaft 3 may have an additional first radial passage other than the first radial passages 53 a to 53 c. The second radial passage of the present invention may be formed by the second radial passages 55 a only without the second radial passages 55 b, 55 c. The drive shaft 3 may have an additional second radial passage other than the second radial passages 55 a to 55 c. The drive shaft 3 may have an additional third radial passage other than the third radial passage 57.

In the compressor according to the first embodiment, the first radial passages 53 a to 53 c, the second radial passages 55 a to 55 c, and the third radial passage 57 have the same diameter. According to the present invention; however, each of the first radial passages 53 a to 53 c may have a lager diameter than those of the second radial passages 55 a to 55 c and the third radial passage 57. Each of the second radial passages 55 a to 55 c may have a lager diameter than those of the first radial passages 53 a to 53 c and the third radial passage 57. The third radial passage 57 may have a lager diameter than those of the first radial passages 53 a to 53 c and the second radial passages 55 a to 55 c.

In the compressor according to the first embodiment, the displacement control valve 33 adjusts the opening degree of the feeding passage 31. The compressor may have, however, a displacement control valve which is configured to adjust the opening degree of the bleeding passage 59.

The present invention is applicable to air conditioners. 

What is claimed is:
 1. A variable displacement swash plate type compressor comprising: a housing having a discharge chamber, a suction chamber, a crank chamber, and a cylinder bore; a drive shaft rotatably supported in the crank chamber; a swash plate disposed in the crank chamber and supported on the drive shaft for rotation with the drive shaft; a piston reciprocally movable in the cylinder bore with a stroke length depending on an inclination angle of the swash plate, the piston forming a compression chamber in the cylinder bore; and a control mechanism configured to change the inclination angle of the swash plate between a maximum inclination angle and a minimum inclination angle by a pressure within the crank chamber, the control mechanism having a feeding passage connecting the discharge chamber and the crank chamber, a bleeding passage connecting the crank chamber and the suction chamber, and a displacement control valve configured to adjust at least one of an opening degree of the feeding passage and the bleeding passage, wherein the bleeding passage includes: an axial passage formed in the drive shaft and extending in an axial direction of the drive shaft; a first radial passage formed in the drive shaft, communicating with the axial passage, and extending in a radial direction of the drive shaft to open on an outer peripheral surface of the drive shaft in the crank chamber; and at least one second radial passage formed in the drive shaft, communicating with the axial passage, and extending in the radial direction of the drive shaft to open on the outer peripheral surface of the drive shaft at a position that is closer to the swash plate than the first radial passage is to the swash plate, and a valve member is disposed on the drive shaft, the valve member is movable in the axial direction of the drive shaft with the swash plate, the first radial passage is in constant communication with the crank chamber, and the valve member is configured to connect the second radial passage to the crank chamber when the swash plate is at the maximum inclination angle or the minimum inclination angle, _(and) to disconnect the second radial passage from the crank chamber when the swash plate is at an intermediate inclination angle that is smaller than the maximum inclination angle and greater than the minimum inclination angle.
 2. The variable displacement swash plate type compressor according to claim 1, wherein the first radial passage opens on the outer peripheral surface of the drive shaft in the crank chamber at a position that is closer to the cylinder bore than the second radial passage is to the cylinder bore.
 3. The variable displacement swash plate type compressor according to claim 1, wherein the housing includes a cylinder block having the cylinder bore and a first housing member cooperating with the cylinder block to define the crank chamber, the first housing member has a sealing member holding the drive shaft to be rotatable and sealing off the crank chamber from the outside of the first housing member, the crank chamber accommodates a lug member disposed on the drive shaft and facing the swash plate, the bleeding passage has a third radial passage formed in the drive shaft, communicating with the axial passage and extending in the radial direction of the drive shaft to open on the outer peripheral surface of the drive shaft between the sealing member and the lug member, and the third radial passage is in constant communication with the crank chamber.
 4. The variable displacement swash plate type compressor according to claim 1, wherein the second radial passage includes a plurality of second radial passages, and the second radial passages open on the outer peripheral surface of the drive shaft at intervals in a circumferential direction of the drive shaft.
 5. The variable displacement swash plate type compressor according to claim 1, wherein the crank chamber accommodates a lug member disposed on the drive shaft and facing the swash plate, the swash plate includes a swash plate arm that is configured to transmit a rotary movement of the drive shaft from the lug member to the swash plate, the swash plate has an insertion hole for receiving the drive shaft and an abutment portion abutting on the outer peripheral surface of the drive shaft in the insertion hole, wherein the abutment portion is disposed opposite to the swash plate arm across an axis of the drive shaft, and the second radial passage opens on the outer peripheral surface of the drive shaft at a position that is located away from the abutment portion in a circumferential direction of the drive shaft. 